US support for gay marriage sees boost over past decade, study finds

Support for gay marriage has seen dramatic gains in the United States over the past decade and now has the backing of a majority of Americans, a new study has shown.

The survey by the non-partisan Public Religion Research Institute found that 53 per cent of Americans say they are in favour of same-sex marriage.

That number reflects a 21-point jump compared to 2003, when only 32 per cent of people said they supported it.

The survey reported a sizeable increase in support for gay marriage among many Americans who regularly attend houses of worship, sometimes viewed as being less receptive to gay rights issues.

The poll found majority support for gay marriage among practicing Jewish Americans (83 per cent), white mainstream Protestants (62 per cent), white Catholics (58 per cent), and Hispanic Catholics (56 per cent).

Hispanic Protestants were split almost down the middle, with 46 per cent saying they were in favour of same-sex marriage and 49 per cent opposed.

Much less support was found among black Protestants (35 per cent) and white evangelical Protestants (27 per cent).

The pollsters said the big increase in support for gay marriage in recent years can be explained in large part by increasing numbers of straight people who say they have a close friend or relative who is gay or lesbian.

The poll found that to be particularly true for Americans in their 20s and early 30s - sometimes referred to as "millennials" - who sometimes go so far as to reject a childhood religion they deem to be homophobic.

In that age bracket, 69 per cent favour gay marriage, the poll found.

"This new research provides further evidence that negative teachings on this issue have hurt churches' ability to attract and retain young people," said the institute's CEO Robert Jones.

"Nearly one-third of millennials who left their childhood religion say unfavourable church teachings about, or treatment of, gay and lesbian people played a significant role in their decision to head for the exit."

The survey queried 4,500 respondents between November 12 and December 18, 2013.